The present invention relates to transmissions and more particularly to a variable gear ratio transmission apparatus for an infinite selection of speeds between the operative speed limits thereof.
Variable gear ratio transmissions may be utilized for a wide variety of applications where it is necessary to transmit a rotational drive. Frequently, it is necessary to utilize a low speed, high torque rotational drive, such as for example in overcoming a load placed on the output shaft. When the load on the output shaft is decreased, it is often necessary or beneficial to utilize a high speed, low torque rotational drive. Thus, when the load on the output shaft is decreasing in response to the drive force applied, it is desirable to change the gear ratio of the transmission to provide a higher gear ratio, sacrificing the less needed torque for the more desirable increased speed.
Increasing the number of gear ratio selections between the absolute operative limits of the transmission apparatus increases the efficiency of the load dispelling capability of the transmission. However, a large number of discreet gear ratios would require an excessive amount of manual operation and would be expensive to produce. Thus, it is desirable to provide a variable gear ratio transmission having the capability for an infinity of gear ratios between the operative limits thereof, and also having the capability for automatic operation.
Prior art variable gear ratio transmissions although functional have frequently had difficulty achieving the necessary efficiency without utilizing a number of belts, pullies, frictional surfaces and other troublesome structures. Hence, it is desirable to provide a variable gear ratio transmission apparatus utilizing only toothed gears for strength and durability.
Accordingly, it is an object of the variable gear ratio transmission apparatus of the present invention materially to alleviate the shortcomings of the prior art.
It is also an object of the variable gear ratio transmission apparatus of the present invention to provide for an infinite selection of speeds between the operative speed limits of the apparatus.
It is a further object of the variable gear ratio transmission of the present invention to provide input differential means for dividing the input rotational force, output differential means for receiving the divided rotational forces and for combining them, and a variable load inhibitor mechanism coupled to one of the divided input rotational forces, thereby to increase the speed of the second divided input rotational force, to increase thereby the speed of rotation transmitted to the combiner differential, and thus finally to increase the output speed of the transmission apparatus.
It is a yet further object of the variable gear ratio transmission apparatus of the present invention to provide a variable load inhibitor mechanism, such inhibitor mechanism including in a preferred embodiment a slip clutch, whereby a feedback mechanism operates for automatically urging the transmission apparatus to seek the highest operable gear ratio.
It is a yet additional further object of the variable gear ratio transmission apparatus of the present invention to provide a variable load inhibitor mechanism including in a preferred embodiment bracketed pinion gears for engaging a ring gear, whereby a brake means is provided to the apparatus.